The present invention relates to an image input device and an image input method, and more particularly to an image input device and an image input method such as a digital still camera and a digital video camera receiving image data obtained by picking up images of an object using a solid image pickup device such as a CCD (Charge Coupled Device) image pickup device.
In this type of image input device as described above, for executing successive operations for picking up images, it is necessary to read out image data and to store the read out data on a memory for each exposure, so that the time required to read out the data is different according to the number of pixels given to a solid image pickup device. Especially, as a large number of pixels are set in a solid image pickup device when a high quality image is to be obtained, a long time is required for reading out the data. For this reason, in recent years, there has been proposed the pixel shift technique for achieving a higher quality image with a smaller number of
Description is made herein for a conventional method of making a high quality image. FIG. 11 is a timing chart for explaining a timing for pixel shift in an example based on the conventional technology. At the timing for executing pixel shift shown in FIG. 11, a time for reading (TR) required for reading out image data from a CCD image pickup device is set in a range, for instance, from {fraction (1/60)} to {fraction (1/15)} seconds, so that a time interval for releasing an electric shutter under the condition in which an exposure time in the first operation and in the second operation is set to a constant period of time, namely a time interval between timings each when an operation for reading out image data is started is obtained by adding a time for pixel shift (TS) to a time for reading (TR). The time for pixel shift (TS) is effected after the time for transferring charges (TF) from photodiodes to vertical CCD.
As described above, however, in the image input device and image input system according to the example based on the conventional technology, the electronic shutter can be released to execute operations for picking up images only at a time interval between the timings when the operation for reading out image data is started, which makes the device inappropriate for picking up an image of a dynamic object which requires high speed successive operations for picking up images thereof and for picking up images of an object by a camera held in user""s hands because these operations must be executed in consideration for jiggle of the camera, and for this reason, pickup of images with the conventional device is limited to operations for picking up a still image of a static object, which does not allow full use of the picking-up capability.
Also, when successive operations for picking up images of an object is to be carried out, and if the object is not bright enough to be photographed, fuzzy images may be obtained due to occurrence of jiggle of the camera.
It is an object of the present invention to provide an image input device and an image input method which can obtain high quality and high resolution images even when an object is not bright enough to be photographed at the time of successive operations for picking up images thereof.
With the image input device and the image input method according to the present invention, when successive operations for picking up images is to be executed, the second operation for picking up an image is controlled at the timing when image data obtained in the first operation for picking up an image is read out from the image pickup device, and after the second operation for picking up the image, the light-shuttering operation is controlled at the timing earlier than the timing when the image data obtained in the second operation for picking up the image is read out from the image pickup device, and then the light to the image pickup device is shuttered, and in addition the operation for emitting strobo-light is controlled so that the time interval from starting of the second operation for picking up an image until emission of second strobo-light is made shorter than the time interval from starting of the first operation for picking up an image until emission of first strobo-light, so that the control for the second operation for picking up an image is not restricted by the timing when image data is read out from the image pickup device, but is immediately executed at the timing when the image data obtained in the first operation for picking up an image is read out, and also the time interval between strobo-light emission in the first operation for picking up an image and strobo-light emission in the second operation for picking up an image is reduced.
Other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.